The present invention relates to pivot angle adjusting means for the arm of a material handling device such as industrial robots.
In the prior art, as shown in FIG. 1, an arm C of an industrial robot, or the like, is adapted to be pivoted through a certain angle by stopping a stopper D attached to the arm C by means of limit switches or oil dampers A. When the arm C is stopped at an intermediate point within said predetermined angle, a stop B such as a limit switch or oil damper is selectively placed in the locus of the pivot movement of the arm C by moving up the stop B therein. In this embodiment, however, since the stop B has a certain thickness, the stop position of the arm C is different when it is moved in the clockwise or the counterclockwise direction, which is rather inconvenient for an accurate positioning of a small piece in the material handling.